package Servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LogoutServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		request.setCharacterEncoding("UTF-8");
		HttpSession session = request.getSession(false);//防止创建Session
		if(session == null){
			response.sendRedirect("Login_Servlet");
			return;
		}
		session.removeAttribute("username");
		session.invalidate();
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		request.getRequestDispatcher("Login_Servlet").forward(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request,response);
	}

}
